#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
	int a = 20;
	int sum = 0;
	while (a>1)
	{
		int b = a / 2;
		sum = sum + b;
		a = b;
	}
	printf("%d", sum + 20+1);
	return 0;
}